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1. The movement of the wind
forces air up the grooves towards the wider ridge channel
2. 50 mm stone wool slab
protects the vapour barrier and safeguards its effectiveness
3. The
vapour barrier consists of Plastic sheet or equal, which prevents rising warm
air from condensing on the membrane. The vapour barrier and junctions with the
rest of the structure must be free from leaks. Joints should overlap by at
least 200 mm, otherwise it can lead to a "chimney effect" in which moist air is
drawn up and freezes inside the structure in winter. The vapour barrier also
ensures that the ventilation system works better throughout the building, since
it eliminates draughts.
4. Grooved stone wool with
high vapour permeability carries moist air along grooves to vents. The slab is
supplied with grooves cut in it that are 20 mm deep and 30 mm wide. Transverse
channels are then cut across the grooves at intersections with items such as
roof windows and fire hatches.
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5. The wider ridge channel
which is cut by hand should be 100 mm wide and 20 mm deep. This channel
connects the grooves that run up the slop to the roof vents.
6. 20 mm stone wool board
helps keep the air in the grooves around 5 degrees warmer than the outside air.
This board forms the base for the outer membrane.
7. Holes are cut in the board
underneath the roof vents.
8. Roof vents made of metal or
plastic finally lead the moist air outside. The roof vents are installed at 6-8
m intervals along the ridge and at 10-12 m intervals in valleys. They have a
diameter of 100 mm and a height of around 400 mm.
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Paroc Air 
